The invention relates generally to stethoscopes, and more particularly to stethoscopes having chestpieces fabricated from polymeric material.
One of the most recognizable tools in the physician""s art is the stethoscope. It is a useful device in that many bodily organs emit sounds that are diagnostic, including the heart, the lungs, the arteries, and the joints. In order to be able to focus on the particular sounds emitted by the organ of interest, and to help the physician discriminate between normal and pathological sounds, stethoscope makers have tried to make more versatile instruments. In particular, much interest in the art has been paid to devices which can either emphasize or de-emphasize particular frequency ranges depending on the physician""s need of the moment.
One of the best known techniques for accomplishing this desirable versatility is to incorporate more than one sound collecting microphone into the chestpiece of the stethoscope. The two most conventional types of microphones are the so-called diaphragm type, which has a thin, usually round, disc of material defining a sound collecting surface, and the so-called bell type, which as an open, concave shape, the lip of which defines a sound collecting surface, to funnel acoustic energy towards the passageways that carry sound to the ears. The bell type microphone is well adapted to convey the lowest tones, such as the main xe2x80x9club-dupxe2x80x9d of the heartbeat. Diaphragm type microphones are most typically tuned to de-emphasize those sounds, and to pass tones of slightly higher frequency. This allows the user of the stethoscope to more readily perceive the sounds typical of heart valve pathologies. One microphone of each type may be placed on the chestpiece to increase the versatility of the stethoscope.
Different materials have been used to fabricate the chestpiece. Some users prefer chestpieces manufactured from metal, which have the advantage of strength, durability, and a pleasant solidity in the hand, and both machining and casting techniques have been used for this purpose. Other users prefer chestpieces manufactured from polymeric materials, which have the advantage of lower manufacturing cost, a lower weight when hung around the user""s neck, and a pleasant warmth in contact with a patient""s body. Both thermoplastic and thermoset polymers have been used for this purpose. Hybrid chestpieces with portions being manufactured from one type of material and portions manufactured from the other type are common.
In one aspect, the present invention provides a chestpiece for a stethoscope, the chestpiece having a novel mix of desirable properties through being fabricated from the group of materials known as xe2x80x9chigh gravity compoundsxe2x80x9d or xe2x80x9cHGCs.xe2x80x9d These compounds are prepared by loading various plastic resins with high density metal powders. In spite of the metallic content, appropriate HGCs can be injection molded, allowing chestpieces according to the present invention to reap the advantage of lower fabrication costs that injection molding provides.
Another advantage that flows from this property is the ability to select aesthetically pleasing shapes beyond those that can be achieved at a practical cost with machining. The use of HGCs also expands the range of colors available compared with metals of similar density, also adding to the aesthetic nature of the stethoscope.
More specifically, the invention provides a chestpiece for stethoscope having a body having at least one sound collecting microphone mounted thereon, the body comprising a high gravity compound, generally having a density of at least about 3 grams/cc. A density of at least about 4.5 grams/cc is also considered useful. In many preferred embodiments, the sound collecting microphone is a microphone of the bell type. As will be discussed with more particularity below, is believed that the higher density is particularly valuable in enhancing the sound gathering qualities of a bell type microphone. Other preferred embodiments will also have a microphone of the diaphragm type, and a mechanism of selecting which microphone is active.